High Resistance Neutral Grounding Systems (HNGR) are used that are limit the fault current up to 5 – 10 A at hospitals, data centers, textile plants, cement plants and other facilities that manufacture with injection to ensure continuity of system. These systems are designed to withstand the fault current continuously.
When determining the fault current in the HNGR system, it is necessary to take into account the capacitive currents and leakage currents flowing from the neutral to the ground due to the capacity of the cables. If the failure current is lower than the zero sequence current, HNGR system runs in failure mode and cannot function.
HNGR systems are optimum solutions from 400 V to 6.9 kV medium voltage system.One of the most important features of HNGR systems is the possibility of detecting the location of the fault. When a phase-to-earth fault occurs in the network, the HNGR system automatically reduces the resistance value by half, so as to flow twice the rated fault current for 1 second (E.g. 1 second 5A, 1 second 10 A). In this way, the fault current changes in such a way that the current can be easily detected even in high phase current and the currents of the outputs in the distribution panels are controlled with the help of a simple clamp meter and fault location is determined.
In contrast to other systems, Aktif HNGR systems automatically detect the location of fault. In the active control panel of the active brand HNGR, if there is a fault in the operation, it is automatically displayed from which distribution point of the fault and from the load which is connected to that distribution point. If the switching equipment used at the plant have the ability to receive the external interrupt signals, the source of the failure can be deactivated.
Also, Aktif HNGR systems automatically monitor and confirm that the system is functional. In case of a system failure, visual and audio alarms are sent to the user. Thus, it maximizes both its own an operational safety .
The following basic parameters and a single-line scheme of the plant, if possible, are required for preparing an offer for HNGR system.
- Phase to phase and phase to ground voltage of the transformer or generator which the resistor is connected
- Fault current level
- Zero sequence current for continuous flow from the neutral point
- Suitable up to 6.9/√3 kV
- Suitable for continuous current up to 10 A and impulse current up to 20 A
- Adjustable fault current, impulse time
- Smart fault detection system to determine the location of fault
- Smart auto control system to check system operation
- Current and voltage monitored on the panel
- Stainless steel resistance material suitable for extreme ambient conditions, resistant to oxidation and corrosion (AISI304, AISI310, AISI316, AISI430, CrAl, CrNi)
- Special mechanical and electrical design to withstand high temperature and extreme current values
- Design and tests in accordance with ANSI-IEEE 32 standard and special specifications
- Spring-wound, edge-wound or grid resistor elements with a cross-section suitable for the nominal current
- Fully-modular, bended and stainless steel bolt connections in order to ensure electrical continuity at high temperature
- High conductivity for high current with bended and cascaded terminal connectors suitable for serial and/or parallel connections with high cross-section, low contact resistance
- High internal insulation and high mechanical resistance against to shocks and sagging thanks to the use of large surface satiated bushings and M16 shear connectors
- Resistance material for which the resistance value does not change with temperature to ensure the fault current stable fault and pulse current
- Standard IP23 Protection Level suitable for outdoor usage and perfect cooling
- Enclosure with standard paint (RAL7035)
- Fully-modular, rigid, strong enclosure design with resistor blocks mounted to the frame for safety lifting from the upper or lower side
- Lockable door with hinges
- Corrosion-resistant handling rings and connectors
- Stainless Steel product and warning labels
- Hot-dipped galvanized, stainless steel, aluminum cabinet
- Painting enclosure in desired color code
- Entry from top or bottom with bushings
- Modular elevation leg suitable for extreme environmental conditions
- Special design for high altitute